The present invention relates to a method of simultaneously producing a number of cigarette rods.
In cigarette manufacturing machines, and as described in U.S. Pat. No. 4,336,812, at least two parallel, side by side strips of paper are fed on to respective conveyor belts, the transportation branches of which extend over a forming bed and through a loading station where a central portion of each strip is fed with a respective continuous layer of shredded tobacco. Downstream from the loading station, the transportation branches of the conveyor belts engage respective variable-section grooves formed along a forming beam fitted to the forming bed, and are deformed transversely by the grooves to gradually wind the respective strips about the respective layers of tobacco to form respective tubular wrappings. Each of the wrappings presents a respective longitudinal lateral appendix, the inner surface of which is gummed by a respective gumming device and then brought into contact with the outer surface of the tubular wrapping to form a respective continuous cigarette rod.
As described in U.S. Pat. No. 4,336,812 referred to above, the inner surfaces of said appendixes face opposite ways to simplify as far as possible the assembly and maintenance of said gumming devices. Such an arrangement, however, seriously complicates any intervention on the forming bed on the part of the operator, as well as the assembly of removable safety covers on the outward-facing part of the forming bed.
To overcome this drawback, the gumming devices are therefore known to be located upstream from the loading station. Even this solution, however, is not without drawbacks, in that, on reaching the loading station, each paper strip presents a lateral portion gummed on the side facing the respective layer of tobacco, so that any stray particles of tobacco from the layer may adhere to the gummed portion of the strip, thus resulting in the formation of defective cigarettes.